Half Nots: 8 Amazing Gynandromorph Animals

Gynandromorph Crab

(images via: VIMS and Habitat News)

One claw two claw red claw blue claw… now hold on a sec, Blue Crab males have blue claws while Blue Crab females have red claws. What to make of a Blue Crab with one blue claw and one red claw, like the one caught by waterman Dave Johnson (above) in a crab pot off the coast of Gwynn’s Island, Virginia on May 21st of 2005? According to Virginia Institute of Marine Science crab expert Rom Lipcius, the crab Johnson caught is a bilateral gynandromorph, meaning it’s split down the middle gender-wise. Lipcius had never seen such a crab before but upon researching the topic came across a similar crab caught near Smith’s Island in 1979.

Gynandromorph Lobster

(images via: ShrimpNow, The Planted Tank and The Lobster Conservancy)

First noted in 1730, gynandromorph lobsters are extremely rare – they do attract notice, however, because the condition is often (but not always) characterized and/or accompanied by the male and female halves sporting different colors. Another way to quickly discern a gynandromorph lobster is to check its claws: American Lobsters normally possess one sharp cutting claw and one larger, blunter, crushing claw.

(image via: Snow Crab Love)

Female lobsters produce eggs whether they’ve mated or not; a gynandromorph lobster was once captured in the wild carrying half the usual complement of eggs. The lobsterman who found the creature donated it to the Maine Department of Marine Resources who monitored the eggs. Though only two eggs were observed to hatch, one of the larvae was male and the other was female.

Gynandromorph Chicken

(images via: Science Buzz and Backyard Chickens)

Gynandromorphism has been observed in birds but not reptiles or amphibians – this may be due to the fact that normal male and female birds are often easy to tell apart, frogs & snakes not so much. Being domestic birds which demonstrate a wide degree of sexual dimorphism, gynandromorph chickens have been documented on numerous occasions throughout history.

(image via: Backyard Chickens)

A gynandromorph chicken looks lopsided due to the differing structure of muscle mass in hens and roosters. As well, the average gynandromorph chicken will typically have a spur on the male half’s foot but not on the female half’s foot. Do gynandromorph chickens crow with the sunrise? Maybe just a little… we can forgive them for going off half cocked.

Gynandromorph Cardinal

(images via: Ohio Birds and Biodiversity / Larry Ammann, Naichisoup, DWMaiden and Finchwench)

The Northern Cardinal is one of more common and colorful birds of North America. They also exhibit a high degree of sexual dimorphism – males and females are roughly similar in size but males are bright red from beak to tail while females display a much more muted feather color pattern.

(image via: Ohio Birds and Biodiversity / Larry Ammann)

Gynandromorph Cardinals are very obvious and even though they’re rare, those with bird feeders in their yards may notice one every once in a while. That is, if the bird’s facing towards the viewer or away: from the side it’s a different story. Other bird species that have exhibited gynandromorphism include songbirds such as Sparrows and Blue-throated Warblers but when it comes to striking displays of gynandromorphism, the Northern Cardinal rules the roost!


(image via: Science Photo Library)

Gynandromorphism is virtually unknown in animals higher than birds. Scientists think this is because in mammals, sexual differentiation occurs as a result of hormonal stimulus. In gynandromorphs, on the other hand, the condition occurs soon after an egg is fertilized and, on occasion, even before when two sperm cells penetrate an unfertilized egg. So-called “human gynandromorphs” such as that depicted in the 16th century woodcut above may merely be hermaphrodites – a whole ‘nother kettle of fish as it were! Can you imagine a human gynandromorph with different colored eyes and hair on either half? Aside of a cosplay convention or Comicon event, neither can we!

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